A Peltier element can provide both heating and cooling depending on the polarity of the applied voltage, or the direction of its operating current. In this case, it is known for the voltage which is applied to the Peltier element, or the operating current, to be regulated. In the case of low-loss voltage regulation via an AC/DCV converter or a DCV/DCV converter, the output voltage cannot be regulated down to the value 0 since the pulse width of the converter cannot be made indefinitely narrow. As such, accurate regulation in the transitional range between heating and cooling is impossible. Furthermore, temperature fluctuations can occur in the transitional range between heating and cooling, since the polarity of the operating voltage for the Peltier element is reversed with a relatively long time constant in the control loop.
The known regulation systems are unsuitable for many applications, such as the temperature stabilization of lasers which are used for transmission purposes.
The particular advantage of the temperature regulation pursuant to the present invention is its accuracy in the transitional range between heating and cooling. In this range, the voltage converter supplies only a low output voltage, so that only a small power loss is required even in the event of periodic switching between heating and cooling.
The use of different time constants for the temperature and for the voltage regulation makes it possible to suppress disturbance influences resulting from the supply voltage.
Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures.